1. State Key Laboratory of Military Stomatology; Department of Operative Dentistry & Endodontics; School of Stomatology; Fourth Military Medical University; Xi'an Shaanxi China
2. Hospital of Stomatology; The Zunyi Medical University; Zunyi Guizhou China
3. Department of Cariology; Restorative Sciences and Endodontics; University of Michigan; Ann Arbor MI USA